The present invention relates to disc drive storage devices. In particular, the present invention relates to microactuators in disc drives.
In a disc drive storage device, data is read from and written to concentric tracks located on a disc using a read head and a write head, respectively. In the disc drive, the read head and write head are supported by a support arm and a suspension assembly, which maintain the head near the disc surface. To position the read head and/or write head over a desired track, the disc drive typically uses a closed-looped servo system that moves the head based on a desired position for the head set by an external controller and a current position of the head determined by a portion of the servo system. In many such servo systems, the head is moved across the disc surface by a voice coil motor, which is connected to the support arm and suspension assembly.
In recent years, it has been proposed that microactuators be added at various locations along the support arm and suspension assembly to provide fine servo positioning control and to increase the frequency response of the servo system. To implement this idea in a manufacturing setting, the microactuators must be tested before they are placed in the drives. Such pre-build testing reduces the losses associated with constructing a drive with faulty components and helps to identify steps in the build process that damage the microactuators. Although current systems provided adequate testing of the microactuators, the tests use an external measuring system that must be properly aligned with the microactuator in order to detect its movement. Because the measuring system is not connected directly to the microactuator, the testing process is prone to error and the step of aligning the equipment takes additional time during the testing phase.
A method and apparatus are provided for testing a microactuator that forms part of a suspension assembly in a disc drive. The method and apparatus test the microactuator before placing the suspension assembly in a disc drive. In the invention, the head is positioned over a track on a disc based in part on servo information read from the disc. At least one input signal is then applied to at least one microactuator on the suspension assembly. Servo information is then read from the disc to determine a change in the position of the head. By comparing the change in the position of the head to the input signal applied to the microactuator, a performance characteristic of a microactuator can be determined.